The Transport Layer Security (TLS) Protocol Version 1.1
RFC 4346

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Network Working Group                                          T. Dierks
Request for Comments: 4346                                   Independent
Obsoletes: 2246                                              E. Rescorla
Category: Standards Track                                     RTFM, Inc.
                                                              April 2006

              The Transport Layer Security (TLS) Protocol
                              Version 1.1

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document specifies Version 1.1 of the Transport Layer Security
   (TLS) protocol.  The TLS protocol provides communications security
   over the Internet.  The protocol allows client/server applications to
   communicate in a way that is designed to prevent eavesdropping,
   tampering, or message forgery.

Dierks & Rescorla           Standards Track                     [Page 1]
RFC 4346                    The TLS Protocol                  April 2006

Table of Contents

   1. Introduction ....................................................4
      1.1. Differences from TLS 1.0 ...................................5
      1.2. Requirements Terminology ...................................5
   2. Goals ...........................................................5
   3. Goals of This Document ..........................................6
   4. Presentation Language ...........................................6
      4.1. Basic Block Size ...........................................7
      4.2. Miscellaneous ..............................................7
      4.3. Vectors ....................................................7
      4.4. Numbers ....................................................8
      4.5. Enumerateds ................................................8
      4.6. Constructed Types ..........................................9
           4.6.1. Variants ...........................................10
      4.7. Cryptographic Attributes ..................................11
      4.8. Constants .................................................12
   5. HMAC and the Pseudorandom Function .............................12
   6. The TLS Record Protocol ........................................14
      6.1. Connection States .........................................15
      6.2. Record layer ..............................................17
           6.2.1. Fragmentation ......................................17
           6.2.2. Record Compression and Decompression ...............19
           6.2.3. Record Payload Protection ..........................19
                  6.2.3.1. Null or Standard Stream Cipher ............20
                  6.2.3.2. CBC Block Cipher ..........................21
      6.3. Key Calculation ...........................................24
   7. The TLS Handshaking Protocols ..................................24
      7.1. Change Cipher Spec Protocol ...............................25
      7.2. Alert Protocol ............................................26
           7.2.1. Closure Alerts .....................................27
           7.2.2. Error Alerts .......................................28
      7.3. Handshake Protocol Overview ...............................31
      7.4. Handshake Protocol ........................................34
           7.4.1. Hello Messages .....................................35
                  7.4.1.1. Hello request .............................35
                  7.4.1.2. Client Hello ..............................36
                  7.4.1.3. Server Hello ..............................39
           7.4.2. Server Certificate .................................40
           7.4.3. Server Key Exchange Message ........................42
           7.4.4. Certificate request ................................44
           7.4.5. Server Hello Done ..................................46
           7.4.6. Client certificate .................................46
           7.4.7. Client Key Exchange Message ........................47
                  7.4.7.1. RSA Encrypted Premaster Secret Message ....47
                  7.4.7.2. Client Diffie-Hellman Public Value ........50
           7.4.8. Certificate verify .................................50
           7.4.9. Finished ...........................................51

Dierks & Rescorla           Standards Track                     [Page 2]
RFC 4346                    The TLS Protocol                  April 2006

   8. Cryptographic Computations .....................................52